The present invention relates in general to an organic EL display device. The invention especially relates to a two-sided display type organic EL display device of the type used for flip phones etc., which includes a main EL display panel and a sub EL display panel, which is disposed on the back side of the main EL display panel. More specifically, the invention relates to an organic EL display device including an absorbent layer(s) having hygroscopic and deoxidizing functions, which protects organic EL display devices disposed within the organic display panel from the external atmosphere.
As miniaturization has progressed in the design of cellular phones and PDAs (personal digital assistance) having display panels (i.e. EL display or liquid crystal display panels), what is being commercialized lately are cellular phones and PDAs having designs which allow a user to keep the phone folded, so that key pad and display panel portions overlap each other during time of non-use (standby time). In addition, recently, there has been an advent of a design providing an additional small display panel on the back side of the aforementioned display panel, so as to allow information to be displayed even while the folded-type cellular phone or PDA is in the folded state (time of non-use).
Products called two-sided display type display devices are being developed as display devices that are suitable for use in cellular phones and PDAs having a second display panel (also referred to as a sub display panel or sub panel) in addition to a conventional display panel (also referred to as a main display panel or main panel), in which the two display panels are arranged oppositely in a back-to-back manner.
Examples of two-sided display type display device, such as one using a liquid crystal display panel as the main display panel and an EL display panel as the sub display panel, and a cellular phone employing such a device are described in JP-A-10-208884 and JP-A-2001-092390.
Furthermore, examples of two-sided EL display device, such as one that emits light from one luminescent layer (organic EL array) formed within an EL display panel toward both sides thereof, are described in JP-A-2002-252089, JP-A-2001-345184 and JP-A-2002-289362. Also, FIG. 5 of JP-A-2002-289362 illustrates a two-sided EL display device in which two luminescent layers respectively emit light to the two sides.